This standard defines the terms, types, basic parameters, requirements, inspection methods, signs and Encasements of angle measuring blocks. It is suitable for angle measuring blocks with specific angles between measurement surfaces. These blocks are usually triangular or tetragonal and are used for accurate Measurement angle. The standard covers the definition of the working angle and reference plane of the angle measuring block, and specifies its accuracy and inspection requirements in detail to ensure the accuracy and Reliability of angle measurement.